The present invention relates to power generators and, more particularly, to an apparatus for converting vibratory motion to electrical energy.
There are situations where transportation conveyances that generally have no available power source, such as freight railcars, shipping containers and the like, have a need for electrical power. For instance, transportation conveyances which incorporate mobile tracking units have a need for efficient and durable power sources capable of being readily integrated therein at a low cost and with a relatively high degree of portability. Typically, the mobile tracking unit includes electrically powered devices, such as radios for determining and reporting vehicle position data from time to time to a remote location, and electronic sensors for sensing and recording predetermined ambient conditions in the vehicle. Photovoltaic power sources, such as solar panels, are subject to disadvantages due to reduced or no power being generated because of poor or no sunlight availability encountered during nights, winter seasons, physical locations, cloudy weather and other circumstances which substantially limit the availability of sunlight to the solar panel.
In the case of rail transportation, for example, when travelling over an average railbed, railcars generally experience significant levels of vibratory motion along a vibration axis which is vertically oriented with respect to the railbed due to unevenness of the railbed and even to wheelset irregularities. Other land-based vehicles, such as tractor trailers and the like, may experience similar vibratory motion. In each case, there is a need to provide an apparatus which can efficiently harness the vibratory motion of the vehicle to provide significant amounts of electrical power regardless of sunlight conditions. Prior techniques which have suggested use of various devices, such as geophones, for converting vibratory motion to electrical energy in general have not been very successful since they are generally designed for relatively small amplitude vibrations. Under relatively large amplitude vibrations (e.g., more than about 1 cm), these devices are prone to magnetic detenting effects which detrimentally reduce their power generating efficiency. Thus there is a need for techniques that advantageously avoid magnetic detenting effects (i.e., the tendency of armatures to become stuck in one preferred spot due to magnetomotive forces) in order to allow for relatively efficient production of electrical power from vibration motion.